BaTb0.3Fe0.7O3−δ: a new proton-conductor-derived cathode for proton-conducting solid oxide fuel cells

Abstract

BaTbO₃ is a much less focused proton-conductor than the traditional BaCeO₃–BaZrO₃ system due to its lower proton conductivity. However, the present study reveals that using BaTbO₃ as the parent material to form the new BaTb_0.3Fe_0.7O_3−δ (BTF) can boost the cathode performance for proton-conducting solid oxide fuel cells (H–SOFCs). Compared with the traditional Fe-doped BaZrO₃ (BZF), the electronic structure of BTF is regulated due to the presence of Tb³⁺ and Tb⁴⁺, leading to more abundant oxygen vacancies and improved oxygen reduction reaction activities compared with BZF, which have been demonstrated by both experiments and first-principles calculations. The slightly decreased proton diffusion by using BaTbO₃ compared with BaZrO₃ is compensated by the greatly enhanced oxygen diffusion and surface exchange abilities, leading to a record-high performance for the BTF cathode compared with other proton conductor-derived cathodes for H–SOFCs.